air in fuel system

[jag7720]

Some how I am getting air into my fuel system. I am having a horrible time fixing it.

Usually it happens when the truck sits for a few hours and on a slope... but it happens on flats occasionally and this morning it happened after idling for 20 minutes and then about 2 miles down the road it die of air in the system.

Sometimes it goes for days or a few weeks with no issue.

I have replaces all my rubber lines. I put on a larger after market spin-on filter. I have one-way valves in the system... one before the filter and one after the fuel pump.

My system:
Tank > rubber line > metal line on frame rail > rubber line to one-way valve > rubber line to filter > rubber line to electric pump > rubber line to one-way valve > rubber line to injection pump


Got any advice as to how to solve this?

 

[1986Blazerk5]

Do you have a electric pump or is that a typo? If there is air in the system the electric fuel pump would push fuel back to the injection pump

 

[jag7720]

Yes I have an electric fuel pump I don't understand what you mean.

Air is getting to the IP or just before it. So it will start and run for 20 or 30 seconds and then starves and dies... Then I have to crank it to pump the air out

 

[1986Blazerk5]

Oh ok never mind i thought you were having trouble starting it with the air leak.

 

[jag7720]

I do but only after it starts and uses the fuel in the line and dies...


I am going to replace the rubber lines again and use injection hose clamps and see if that helps

 

[1986Blazerk5]

I would look between the fuel pump and the injection pump for leaks. Also did you clean the return line valve on the injection pump?

 

[jag7720]

After getting it started this morning and driving 3 miles to work it sat all day on a flat surface.... got in after work and had the same issue... it starts and then runs dry and then I have to crank it forever to get the air out.

The IP is new so I would think the return ball valve is good but I'll pull it off tomorrow and take a look.

Tonight I replaced the line and clamps from the filter to the lift pump and from the lift pump to the IP. Got the lines filled again and started the engine... ran it for few minutes... Well see in the morning.

 

[1986Blazerk5]

Are you sure your fuel pump is turning on? The fuel pump would push fuel back up to the injection pump. It sounds like you are having the same problem i did, until i added a electric fuel pump, then it stopped. Because by turning the pump on before starting it would push fuel up to the injection pump.

 

[pmramsey]

Your truck could be plumbed for a second fuel tank. If a second tank is not installed, there will be a piece of rubber at the end of the line at a "Y" where the second tank would joint the system. I is located in the area under the passenger side. This rubber had crapped out on my unit. It will suck air.

 

[pistonium]

I'll just throw in another thought here....maybe an intermittent fuel line restriction/clogging? When it is running, do you have all the fuel you need? (going up a hill at wide open throttle?). Maybe worth pulling the inlet screen in the tank and checking....also try to see if you have full fuel flow at the inlet to the IP with the electric pump running next time you have the problem.....

Maybe a piece of crap is in the lines somewhere and occaisionally blocks the line and sometimes moves to let fuel by.....or there is a pile of crud in the tank and when parked just right it all ends up at the intake screen; otherwise it runs?

 

[pistonium]

and check the solenoid valve at the IP for fuel shutoff; maybe an intermittent electrical problem on the lead in to the valve or a problem with the solenoid itself.

sometimes air in the filter can cause intermittent problems....is the filter at a high spot in the system and fully bled of air? Could the spin on filter be leaking air in at the gasket?

 

[jag7720]

I put new rubber lines and the none cutting style clamps from the filter to the pump to the IP. A clogged line... I don't think that is it.

Same thing this morning.

The pump works. I can hear it thumping and when I open the line right before the IP fuel flows out.

I took that screen out of the tank last year... now I run a small pre-filter before my main filter.

I'll check the IP solenoid... but there is nothing near it as I have a banks turbo and the pressure manifold is small and away from the IP. Plus it runs for about 30 seconds and then shuts off.


Now my batteries are dead in this cold

 

[jag7720]

I moved the fuel pump to the frame rail on the passenger side where the steel line goes from inside the frame to outside.

I turned on the pump and could see the pump pushing fuel and air (since I opened the line to put the pump in). I started it and it ran and died as usual but then I only had to crank it for about 5 seconds before it started again.

I drove it home and let is sit all night. This morning is started up and stayed running. No issue... I'll keep an eye on it this week and see if that solved the issue.